首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
Wild evening primrose species (Oenothera spp.) native to Argentina, have been suggested as a new crop for irrigated valleys of semi-arid Patagonia. This paper describes patterns of biomass allocation, morphological traits related to stress-tolerance and seed-yield in four species of Oenothera grown in a common garden at three plant densities. Wild and domesticated species are compared. The effect of resource availability on those traits during three phenological stages (vegetative, reproductive and maturity) is described. Native species were characterized by traits related to stress-tolerance (high root allocation and low specific leaf area) during the vegetative stage. This suite of traits resulted in low biomass accumulation and low seed-yield. The domesticated O. biennis was characterized by a combination of traits related to stress-tolerance (low specific leaf area) and high productivity (high leaf allocation and leaf area ratio and low root allocation). Domesticated species accumulated more biomass than natives. Total biomass and total non-structural carbohydrates present in roots were positively correlated to seed-yield.Oenothera biennis showed the highest seed-yield, although this species showed yield instability in response to changes in the environmental quality. No changes in seed-yield in response to plant density were recorded for either O. lamarckiana or native species. Oenothera biennis showed an optimum density of 20 plants m−2 and yielded 260 g m−2, a seed-yield similar to that reported in other countries. Low seed-yield of native species is major drawback that must be overcome. Improving seed-yield in these species could be possible by selection oriented to increase total biomass. Since no detrimental effect of density was found in O. lamarckiana and natives, a higher plant density might increase yield production per unit area.  相似文献   

2.
The antioxidant potential of milling fractions from breadwheat and durum   总被引:1,自引:0,他引:1  
The effect of primary processing, namely milling, on the phenolic content and antioxidant capacity of two wheat cultivars, namely Canada Western Amber Durum (Triticum turgidum L. var. durum) and Canada Western Red Spring (Triticum aestivum L.) was studied. The milling products: bran, flour, shorts and feed flour fractions were examined. In addition, semolina was an end-product of durum wheat milling. Antioxidant activity of wheat phenoliocs was evaluated using oxygen radical absorbance capacity, inhibition of photochemiluminescence, the Rancimat method, and inhibition of oxidation of low-density lipoprotein cholesterol and deoxyribonucleic acid. The phenolic composition of wheat extracts was determined using high performance liquid chromatography. Bran showed the highest antioxidant activity whereas the endosperm possessed the lowest in both cultivars examined. The phenolic compounds are concentrated in the outermost layers namely the bran. The consumption of wheat with bran in the form of whole grain may provide beneficial health effects.  相似文献   

3.
This study investigates the development of thermoset plastics from plant-based oils (e.g., linseed, soybean, cottonseed, oilseed radish, and peanut oils) using an optimal process of solvent-free epoxidation. The epoxidation of plant oils can be accomplished economically by reacting the double bonds of fatty-acids with hydrogen peroxide. During the solvent-free process catalyzed by the ion-exchange resin, we observed that the influence of several variables was important: the molar ratio of hydrogen peroxide to unsaturation, acetic acid to unsaturation, and temperature. The epoxidation of plant oils was determined from the liquid mixture and the composite matrix by thermal and spectroscopic analyses. Compounds with a higher double-bond (iodine) value showed higher oxirane oxygen percent and selectivity, and a higher hydroxyl value because of a greater possibility of attack by solutions causing side reactions. Lower iodine values indicated fewer epoxy groups and selectivity, and a lower hydroxyl value. Benzyl pyrazinium hexafluoroantimonate (BPH) yielded good thermal curing properties; as little as 1% added to the plastics produced light-weight composites. Epoxidized linseed oil promises the highest modulus and impact resistance due to the largest number of double bonds to contribute more epoxy groups and the large proportion of linolenic acids to produce epoxy groups rapidly.  相似文献   

4.
5.
Between 2006 and 2008, 120 isolates of Sclerotinia sclerotiorum from the Jiangsu Province of China were characterized for the baseline sensitivity to boscalid, a new active ingredient that interferes with succinate ubiquinone reductase in the electron transport chain of fungi. The isolates collected between 2006 and 2008 all showed similar sensitivity to boscalid. Baseline sensitivities were distributed as unimodal curves with mean EC50 values of 0.17 ± 0.09 μg ml−1 for inhibition of mycelial growth. Inhibition of mycelial growth of isolates whether they had resistance to carbendazim or, dimethachlon or dual resistance to both carbendazim and dimethachlon was similar, suggesting that there was no cross-resistance between boscalid and MBC/dimethachlon already in commercial use. In field trials, the treatments boscalid (50% WG), at 125, 187.5 and 250 g ai ha−1 provided higher control efficacies of 65.2, 69.0 and 75.1%, respectively, than the treatments carbendazim (50% WP), at 750 g ai ha−1 and dimethachlon (46% WP), at 690 g ai ha−1 with control efficacies of 18.9 and 44.6%, respectively.  相似文献   

6.
Microorganisms such as fungi are one of the most important factors that cause oxidative processes during postharvest stage and consequently deterioration of agriculture products would not be unexpected. On the other hand, high antioxidant properties of industrial by-products of pomegranate propose them as powerful antioxidant and antifungal substances. So to investigate the antioxidant and antifungal properties of pomegranate, two independent factorial experiments based on randomized design with 5 replications were conducted. In the first experiment the effect of 3 different parts of pomegranate (peel, seed and leaf) and 2 different kinds of extracts (aqueous and methanolic) with 4 concentrations (0, 500, 1000 and 1500 ppm) were investigated on 3 postharvest fungi (Penicillium italicum, Rhizopus stolonifer and Botrytis cinerea). In the second experiment antioxidant capacity and phenolic content were measured for two different extracts from different parts. Based on the results the methanolic extract showed the highest inhibitory effects on the mycelia growth (IMG) and spore germination (ISG) with 49.82 and 41.25% respectively. On the other hand, peel and seed extracts had more inhibitory effect (IMG and ISG) than leaf extract. The phenolic content of peel extract were also measured 2.8 fold higher than pomegranate leaf extract and antioxidant capacity of peel, seed and leaf extracts of pomegranate were 55.3%, 35.7% and 16.4% respectively. Therefore, it seems that the high percentage of phenolic content in the peel and seed of pomegranate could cause the high antifungal and antioxidant activity of their extracts.  相似文献   

7.
Viable propagules ofVerticillium albo-atrum were recovered from roots and stems of naturally infected weeds and sunflower cultivars before or after burial in the field and from stems and roots of certain non-infested crops after burial in the field for seven months.Verticillium dahliae was recovered less frequently, then only from the roots ofSolanum nigrum (black nightshade). Survival of these pathogens after burial for 7 months varied considerably, ranging from 38 to 58% in sunflower stems and from 19 to 235% in roots of weeds. In stems of weeds and crops which did not contain propagules ofV. albo-atrum before burial, the fungus was recovered consistently after burial, indicating that saphophytic colonization probably occurred during interment.  相似文献   

8.
甘蓝型油菜带柄子叶高频率再生植株的研究   总被引:12,自引:0,他引:12  
以甘蓝型油菜(Brassica napus)912品系带柄子叶为外植体,不同浓度6-BA与NAA激素组合的分化培养基诱导芽苗的分化,开展提高甘蓝型油菜带柄子叶再生频率的因素研究.发现甘蓝型油菜912品系带柄子叶在不同激素及浓度的6-BA与NAA组合中的再生频率、分化率存在显著差异.通过无菌苗苗龄、诱导分化前2,4-D的预培养以及添加AgNO3等因素的系统分析,结果表明甘蓝型油菜912品系带柄子叶在诱导分化前经过1.0mg/L 2,4-D的MS培养基中预培养3d,在最适培养基MS0 6-BA 4.0mg/L NAA 0.02mg/L 3.5mg/L AgNO3中,可较大程度地提高植株再生频率,再生频率和分化频率分别为70%和269.5%,初步建立了甘蓝型油菜912品系的高频率再生植株体系.  相似文献   

9.
在人工接种高病害压条件下,对当前生产上应用的13个油菜双低和杂交品种及14份资源材料进行了 对芜菁花叶病毒( TuMV)的抗性鉴定。结果表明,参试的13个油菜品种均不抗TuMV,但感病性低于对照品种中油 821。14份油菜资源材料间抗性差异显著,有3份材料表现高抗和中抗。大部分油菜推广品种表现的高发病率和 病情指数表明在病害流行地区和年份,这些品种不足以抵挡病毒病造成的损失。  相似文献   

10.
油菜内生枯草芽孢杆菌(Bacillus subtilis)BY-2产生2种类型的抗真菌物质,一种是挥发性的de物质,可以有效地抑制油菜菌核病菌的生长;另一种是分泌到培养液中的物质。重点研究第二类抗菌物质的提取和纯化分析方法。试验证明BY-2 产生和积累高效抑制油菜菌核病菌(Sclerotinia sclerotiorum (Lib.)de Bary)生长的细胞外分泌型物质,其发酵上清液与油菜菌核病菌对峙培养形成了2.8 cm的抑菌圈;采用离心收集发酵液上清液、调节酸性条件、甲醇溶解和Sephadex G25葡聚糖凝胶柱层析等方法,可以沉淀、萃取收集和纯化该物质,而且收集率高、活性强、纯度高。  相似文献   

11.
对福建省宁德市2006-2009年1738份茶叶样品,采用气相色谱仪检测三氯杀螨醇、氰戊菊酯、氯氰菊酯、甲氰菊酯、滴滴涕等农药残留含量,获取相应的检测数据,以国内制定的农药最大残留量为指标进行分析评估,结果表明,2006-2009年该市茶叶中农药残留检出超标率呈逐年下降的趋势,但是滴滴涕等农药仍有较高检出率,说明菊酯类农药较普遍使用应引起监管部门足够的重视,以防止该类农药的泛滥使用,并就此提出相应的农药残留控制措施。  相似文献   

12.
高油玉米花粉直感等遗传效应对普通玉米产量及品质的影响   总被引:21,自引:6,他引:21  
通过大田试验筛选出了高油玉米为普通玉米单交种授粉来达到增产和提高普通玉米含油量、蛋白质含量的组合。所筛选出的3个组合(SN3×HO115、SN3×HO298、SN98-1×HO298)中,与普通玉米自身相比较,子粒产量分别提高1 457.6、1 465.1和1 363.1 kg/hm2,油产量分别提高296.1、323.3和300.8 kg/hm2,蛋白质产量分别提高296.0、15.6和389.6 kg/hm2。高油玉米的花粉直感及与普通玉米杂交的杂交优势效应在大田玉米生产中应用前景广阔。  相似文献   

13.
To improve the economic viability of the biofuel production from biomass resource, a value-added lignin byproduct from this process is increasingly important. Antioxidant and antimicrobial activities of lignin extracted from residue of corn stover to ethanol production were investigated. The lignin extracts exhibited strong antioxidant activities in hydrophilic oxygen radical absorbance capacity (ORAC) assay and Folin-Ciocalteu test. The extracts also exhibited antimicrobial activities against Gram-positive bacteria (Listeria monocytogenes and Staphylococcus aureus) and yeast (Candida lipolytica), but not Gram-negative bacteria (Escherichia coli O157:H7 and Salmonella Enteritidis) or bacteriophage MS2. Different extraction conditions (temperature and residue/solvent ratio) affected the antioxidant and antimicrobial activities of lignin extracts. Generally, the bioactivities of lignin extracts were consistent with FTIR analysis results. Lignin byproducts showed the potential for their antioxidant and antimicrobial application.  相似文献   

14.
Effects and fate of biochar from rice residues in rice-based systems   总被引:8,自引:0,他引:8  
Although crop residues constitute an enormous resource, actual residue management practices in rice-based systems have various negative side effects and contribute to global warming. The concept of a combined bioenergy/biochar system could tackle these problems in a new way. Rice residues would be used for energy production, thereby reducing field burning and the use of fossil fuels, and the biochar by-product could help to improve soils, avoid methane emissions, and sequester carbon in soils. To examine some of these promises, we conducted field experiments from 2005 to 2008 in three different rice production systems. Objectives were to study the effect of biochar from rice husks on soil characteristics, assess the stability of carbonized rice residues in these different systems, and evaluate the agronomic effect of biochar applications. The results showed that application of untreated and carbonized rice husks (RH and CRH) increased total organic carbon, total soil N, the C/N ratio, and available P and K. Not significant or small effects were observed for soil reaction, exchangeable Ca, Mg, Na, and the CEC. On a fertile soil, the high C/N ratio of CRH seemed to have limited N availability, thereby slightly reducing grain yields in the first three seasons after application. On a poor soil, where the crop also suffered from water stress, soil chemical and physical improvements increased yields by 16-35%. Together with a parallel study including methane and CO2 emission measurements at one site, the results strongly suggest that CRH is very stable in various rice soils and systems, possibly for thousands of years. However, the study also showed that CRH was very mobile in some soils. Especially in poor sandy soil, about half of the applied carbon seemed to have moved below 0.30 m in the soil profile within 4 years after application. We concluded that biochar from rice residues can be beneficial in rice-based systems but that actual effects on soil fertility, grain yield, and soil organic carbon will depend on site-specific conditions. Long-term studies on biochar in field trials seem essential to better understand biochar effects and to investigate its behavior in soils.  相似文献   

15.
The yield and persistency of grass species within a managed sward are a major consideration when determining species mixtures for either long-term or short-term sward management systems. Perennial ryegrass is lower yielding but more persistent than Italian ryegrass. Hybrid ryegrass, an interspecies cross between perennial and Italian ryegrass, may be higher yielding than perennial ryegrass and more persistent than Italian ryegrass. Therefore, the yield and persistency of hybrid ryegrass was investigated in Northern Ireland in five experiments, each harvested over five consecutive years, and compared with that of Italian ryegrass, perennial ryegrass and timothy. The performance of the five grass species were in the expected order; Italian ryegrass was higher yielding than hybrid ryegrass, which was higher than perennial ryegrass, with timothy the lowest, whereas perennial ryegrass and timothy had significantly higher sward densities than the hybrid and Italian ryegrasses. In addition, it was found that the rate of decline in yield and sward density with age was the same for all species. Consequently, this study indicated that the higher yielding Italian and hybrid ryegrasses could continue to out-perform perennial ryegrass for 5 years, opening the possibility of more extensive farming use of these species, particularly in Northern Ireland.  相似文献   

16.
Leaf mass per area (LMA) is a parameter the variability of which contributes to architectural plasticity. However its variations according to environment remain not completely understood. We hypothesise that LMA variations of winter oilseed rape (WOSR) follow an ontogenetic trajectory that can be modified by the environment. This was assessed at plant and leaf levels comparing four genotypes field-grown under different environmental conditions characterised by year and nitrogen nutrition. Leaves of the main stem of plants sampled between emergence and harvest were surfaced, oven-dried and weighed to calculate LMA of each individual leaf. At the plant level, LMA presented a common ontogenetic trajectory, which increases from seedling emergence to bolting and from then on decreases. Variations in LMA were related to the variations in plant demand, LMA decreased when demand increased. The trajectory was modified by low N nutrition that increased LMA but differently according to year and genotype, reflecting the plant plasticity. At the leaf level, variations for each individual leaf were related to the variations at the plant level. Plant plasticity and genotypic variability of the responses of LMA to N deficiency seemed to be related to differences in biomass allocation between leaves and stems.  相似文献   

17.
《Field Crops Research》2002,79(1):39-51
Maize (Zea mays L.) hybrids differ in their response to plant population density. Enhancements in tolerance to crowding have been obtained around the world as the result of selecting the best yielding hybrids at dense stands over a wide testing area. However, the understanding of morpho-physiological determinants of maize endurance to the population density stress still needs improvement. This study aimed to evaluate the response of maize hybrids from different eras grown extensively in Brazil to the increase in plant sowing density and to identify agronomic traits that can account for the contrasting tolerance to high interplant competition. The trial was conducted in Lages, southern Brazil, during the growing seasons of 1999/2000 and 2000/2001. A split plot design was used. The double-cross hybrids Agroceres 12, Agroceres 303, and the single-cross hybrid Cargill 929, commercially released during the 1970s, 1980s and 1990s, respectively, were evaluated in the main plots. Four plant population densities were tested in the split plots: 25,000, 50,000, 75,000 and 100,000 plants ha−1. Maize was sown in no-tillage system, having black oat as the preceding winter crop. Canopy architecture parameters, tassel dry matter accumulation, flower synchrony, grain yield and its components were evaluated. The older hybrids Agroceres 12 and Agroceres 303 out-yielded modern-hybrid C 929 at the lowest plant population density. The increase in plant population increased barrenness, lengthened the anthesis–silking interval and decreased kernel set per ear more drastically for the older than for the modern-hybrid. Consequently, the higher the number of plants per unit area, the greater the edge between grain yield and kernel number per area of C 929 in relation to its older counterparts. Current hybrid’s better performance at supraoptimum plant population densities was favored by three sets of traits. First, by lower dry matter partition to the tassel, stimulating a more balanced allometric relationship between male and female inflorescence. Second, by a more compact canopy architecture, with shorter plants, fewer and more upright leaves, enhancing solar radiation interception. Third, by low ear insertion to plant height ratio, promoting greater resistance to stalk lodging. These traits contributed to higher grain yield and positive response to higher densities in the modern-hybrid.  相似文献   

18.
Payenapara lleloneura Kurz. (Kan-zaw), an endemic medicinal plant only found in Tanintharyi Region of Myanmar, is widely used in the treatment of various cancer and different ailments. In the present research, the seeds were phytochemical investigated for their nutritional potential for their use as functional foods or novel diet oil resources. Nutritional evaluation showed that the seeds are rich in fats and carbohydrates (soluble sugars and starch). Fatty acid analyses showed that the seeds accumulate very rich α-eleostearic acid (α-ESA, 18:3Δ9cis,11trans,13trans), an important conjugated fatty acid, up to more than 70 ​% of total fatty acids. The seed oil derived from the Kan-zaw tree contains approximately 3.25 ​% β-eleostearic acid (18:3Δ9trans,11trans,13trans), an unusual conjugated fatty acid that imparts a potent anticancer application and industrially important drying qualities to Kan-zaw oil. Physicochemical properties of the Kan-zaw seeds were examined; petroleum ether (60–90 ​°C) extract of seed oils were also investigated for the saponification value, iodine value and estimation of acid value. Further, the present study investigated cytotoxic potential of ethanol, methanol, acetone, chloroform Kan-zaw seed extracts and commercial Kan-zaw oil against human cervical cancer cell line (HeLa). The Kan-zaw extracts and oil have shown significant anticancer activity on HeLa cells.  相似文献   

19.
American Journal of Potato Research - The main point in the proposed system of virus designation is the combination into simple formulas of symbols, standing for essential and mutually independent...  相似文献   

20.
合理轮作对作物生产有积极的促进作用.为明确不同轮作模式和前茬作物对旱地胡麻生长发育和籽粒产量的影响,通过田间长期定位试验,研究了胡麻-胡麻-胡麻-胡麻(FFFF)、胡麻-小麦-马铃薯-胡麻(FWPF)、胡麻-马铃薯-胡麻-小麦(FPFW)、胡麻-胡麻-小麦-马铃薯(FFWP)、胡麻-小麦-胡麻-马铃薯(FWFP)和胡麻...  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号